linux-kernel - Re: [PATCH v3 2/4] net: stmmac: dwc-qos: Add FSD EQoS support

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Date:   Mon, 14 Aug 2023 21:50:44 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Sriranjani P <sriranjani.p@...sung.com>, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        conor+dt@...nel.org, richardcochran@...il.com,
        alexandre.torgue@...s.st.com, joabreu@...opsys.com,
        mcoquelin.stm32@...il.com, alim.akhtar@...sung.com,
        linux-fsd@...la.com, pankaj.dubey@...sung.com,
        swathi.ks@...sung.com, ravi.patel@...sung.com
Cc:     netdev@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Chandrasekar R <rcsekar@...sung.com>,
        Suresh Siddha <ssiddha@...la.com>
Subject: Re: [PATCH v3 2/4] net: stmmac: dwc-qos: Add FSD EQoS support

On 14/08/2023 13:25, Sriranjani P wrote:
> The FSD SoC contains two instance of the Synopsys DWC ethernet QOS IP core.
> The binding that it uses is slightly different from existing ones because
> of the integration (clocks, resets).
> 
> For FSD SoC, a mux switch is needed between internal and external clocks.
> By default after reset internal clock is used but for receiving packets
> properly, external clock is needed. Mux switch to external clock happens
> only when the external clock is present.
> 
> Signed-off-by: Chandrasekar R <rcsekar@...sung.com>
> Signed-off-by: Suresh Siddha <ssiddha@...la.com>
> Signed-off-by: Swathi K S <swathi.ks@...sung.com>
> Signed-off-by: Sriranjani P <sriranjani.p@...sung.com>
> ---


> +static int dwc_eqos_setup_rxclock(struct platform_device *pdev, int ins_num)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	struct regmap *syscon;
> +	unsigned int reg;
> +
> +	if (np && of_property_read_bool(np, "fsd-rx-clock-skew")) {
> +		syscon = syscon_regmap_lookup_by_phandle_args(np,
> +							      "fsd-rx-clock-skew",
> +							      1, &reg);
> +		if (IS_ERR(syscon)) {
> +			dev_err(&pdev->dev,
> +				"couldn't get the rx-clock-skew syscon!\n");
> +			return PTR_ERR(syscon);
> +		}
> +
> +		regmap_write(syscon, reg, rx_clock_skew_val[ins_num]);
> +	}
> +
> +	return 0;
> +}
> +
> +static int fsd_eqos_clk_init(struct fsd_eqos_plat_data *plat,
> +			     struct plat_stmmacenet_data *data)
> +{
> +	int ret = 0, i;
> +
> +	const struct fsd_eqos_variant *fsd_eqos_v_data =
> +						plat->fsd_eqos_inst_var;
> +
> +	plat->clks = devm_kcalloc(plat->dev, fsd_eqos_v_data->num_clks,
> +				  sizeof(*plat->clks), GFP_KERNEL);
> +	if (!plat->clks)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < fsd_eqos_v_data->num_clks; i++)
> +		plat->clks[i].id = fsd_eqos_v_data->clk_list[i];
> +
> +	ret = devm_clk_bulk_get(plat->dev, fsd_eqos_v_data->num_clks,
> +				plat->clks);

Instead of duplicating entire clock management with existing code, you
should extend/rework existing one.

This code is unfortunately great example how not to stuff vendor code
into upstream project. :(

> +
> +	return ret;
> +}
> +
> +static int fsd_clks_endisable(void *priv, bool enabled)
> +{
> +	int ret, num_clks;
> +	struct fsd_eqos_plat_data *plat = priv;
> +
> +	num_clks = plat->fsd_eqos_inst_var->num_clks;
> +
> +	if (enabled) {
> +		ret = clk_bulk_prepare_enable(num_clks, plat->clks);
> +		if (ret) {
> +			dev_err(plat->dev, "Clock enable failed, err = %d\n", ret);
> +			return ret;
> +		}
> +	} else {
> +		clk_bulk_disable_unprepare(num_clks, plat->clks);
> +	}
> +
> +	return 0;
> +}
> +
> +static int fsd_eqos_probe(struct platform_device *pdev,
> +			  struct plat_stmmacenet_data *data,
> +			  struct stmmac_resources *res)
> +{
> +	struct fsd_eqos_plat_data *priv_plat;
> +	struct device_node *np = pdev->dev.of_node;
> +	int ret = 0;
> +
> +	priv_plat = devm_kzalloc(&pdev->dev, sizeof(*priv_plat), GFP_KERNEL);
> +	if (!priv_plat) {
> +		ret = -ENOMEM;

return -ENOMEM

> +		goto error;
> +	}
> +
> +	priv_plat->dev = &pdev->dev;
> +	data->bus_id = of_alias_get_id(np, "eth");

No, you cannot do like this. Aliases are board specific and are based on
labeling on the board.

> +
> +	priv_plat->fsd_eqos_inst_var = &fsd_eqos_clk_info[data->bus_id];
> +
> +	ret = fsd_eqos_clk_init(priv_plat, data);
> +
> +	data->bsp_priv = priv_plat;
> +	data->clks_config = fsd_clks_endisable;
> +	data->rxmux_setup = dwc_eqos_rxmux_setup;
> +
> +	ret = fsd_clks_endisable(priv_plat, true);
> +	if (ret)
> +		goto error;
> +
> +	ret = dwc_eqos_setup_rxclock(pdev, data->bus_id);
> +	if (ret) {
> +		fsd_clks_endisable(priv_plat, false);
> +		dev_err_probe(&pdev->dev, ret, "Unable to setup rxclock\n");

The syntax is: return dev_err_probe().

> +	}
> +
> +error:
> +	return ret;
> +}

....


Best regards,
Krzysztof